What should I expect and do after being ordered to have an abdominal aortic ultrasound?

Abdominal Aortic Ultrasound: What to Expect and Do

For an abdominal aortic ultrasound, you should fast for 8-12 hours before the test to reduce intestinal gas and improve image quality. 1 This painless, non-invasive procedure will measure your aortic diameter to screen for abdominal aortic aneurysm (AAA).

Preparation for the Test

• Fasting requirement: Fast for 8-12 hours before your appointment 1
• Medication: Continue taking your regular medications with small sips of water unless instructed otherwise
• Clothing: Wear loose, comfortable clothing that allows easy access to your abdomen
• Duration: The test typically takes 15-30 minutes

During the Procedure

The ultrasound technician will:

1. Position you lying on your back on an examination table
2. Apply a gel to your abdomen to improve sound wave transmission
3. Move a transducer (a handheld device) over your abdomen to capture images
4. May ask you to hold your breath briefly during certain parts of the exam
5. Take measurements of your aorta in both longitudinal and transverse views 1

You may be asked to change positions during the exam, including lateral decubitus (side-lying) positions to get better images 1.

What the Test Measures

The ultrasound measures the diameter of your abdominal aorta from the outer edge to the outer edge of the aortic wall 1. This measurement helps determine if you have an abdominal aortic aneurysm (AAA), which is defined as:

• An aortic diameter exceeding 3 cm 2
• A focal dilation ≥1.5 times the normal adjacent arterial segment 2

After the Test

• You can resume normal activities immediately after the test
• No recovery period is needed
• You can eat and drink normally

Understanding Your Results

Your doctor will review the results with you. Based on the findings:

• Normal aorta (less than 3 cm): No further testing needed unless you have risk factors requiring periodic screening
• Small aneurysm (3-4 cm): Follow-up ultrasound every 3 years 3
• Medium aneurysm (4-4.9 cm): Annual follow-up ultrasound 3
• Large aneurysm (5-5.5 cm): Follow-up ultrasound every 6 months 3
• Very large aneurysm (≥5.5 cm for men, ≥5 cm for women): Your doctor will likely recommend intervention rather than continued surveillance 3

Important Considerations

• Ultrasound is highly accurate with sensitivity of 95% and specificity near 100% when performed with adequate quality assurance 1
• One-time screening is usually sufficient if normal; rescreening those with normal aortic diameter on initial screening provides negligible health benefit 1
• If an aneurysm is detected, your doctor may order additional imaging such as CT angiography for more detailed evaluation before intervention 1
• Factors that may affect ultrasound quality include obesity and excessive bowel gas 1

When to Contact Your Doctor

Contact your doctor immediately if you experience:

• Sudden severe abdominal or back pain
• Persistent abdominal or back pain
• Symptoms of shock (rapid heartbeat, dizziness, fainting)

These could indicate a complication requiring immediate medical attention.